1. Field of the Invention
The present invention relates to a control system for an apparatus for protecting the head portion of a vehicle occupant which, at the time a predetermined high load is applied to a side portion of a vehicle body, jets gas from an inflator so as to inflate an air bag body in a curtain-like shape from a front pillar portion along a roof side rail portion due to the gas.
2. Description of the Related Art
Control systems for apparatuses for protecting the head portion of a vehicle occupant have been proposed which, in order to improve the vehicle occupant head portion protecting performance at the time when a predetermined high load is applied to a side portion of the vehicle, inflate, in a curtain-like shape and along a window glass, an air bag body which is accommodated in a folded-up state so as to extend from the front pillar portion along the roof side rail portion. The structure described in WO 96/26087, which discloses such a control system for an apparatus for protecting the head portion of a vehicle occupant, will be described hereinafter.
As illustrated in FIG. 6, a vehicle occupant protecting apparatus 100 includes as the main structural components thereof an elongated duct 106, an air bag body 112, an inflator 116, and a belt-like strap 118. The elongated duct 106 is disposed so as to extend from a front pillar portion 102 along the roof side rail portion 104. The air bag body 112 is accommodated within the duct 106 in a folded-up state, and is fixed to the vehicle at a front end fixing point 108 and a rear end fixing point 110. The inflator 116 is connected to the rear end portion of the duct 106 via a hose 114, and jets gas at the time a predetermined high load is applied to a side portion of the vehicle. One end portion of the belt-like strap 118 is fixed to the vehicle, and the other end portion thereof is fixed to the rear end portion of the air bag body 112. The air bag body 112 is formed by connecting a plurality of cells 120 which are each formed in a substantially cylindrical configuration and which are disposed such that the longitudinal directions thereof are substantially the vertical direction of the vehicle.
In accordance with the above-described structure, when a predetermined high load is applied to a side portion of the vehicle, gas is jetted out from the inflator 116. The jetted gas flows, via the hose 114 and the duct 106, into the respective cells 120 of the air bag body 112 which is folded up. As a result, the cells 120 inflate into substantially cylindrical shapes whose longitudinal directions are substantially the vertical direction of the vehicle. The air bag body 112 thereby inflates in a curtain-like shape along a window glass 122. Further, because the rear end portion of the air bag body 112 is connected to the vehicle via the strap 118, the rear end side of the air bag body 112 is reliably disposed at the inner side of the upper portion of a center pillar portion 124.
However, in the above described system for controlling an apparatus for protecting the head portion of a vehicle occupant, the air bag body 112 inflates and unfolds between the head portion of the vehicle occupant and a portion of the vehicle, e.g., the side door glass. Therefore, if the vehicle is turning or a roll is generated at the vehicle or the like, because the vehicle occupant is swung toward the side portion of the vehicle, the gap between the vehicle occupant and the side portion of the vehicle, i.e., the space for the unfolding of the air bag body 112, becomes small.